In the Wideband Code Division Multiple Access (Wideband CDMA, and WCDMA for short) system, with respect to the characteristics of the high speed packet data such as asymmetry, high peak rate and short activation time, in order to efficiently utilize radio spectrum resources and increase the downlink peak rate and cell throughput, the 3rd Generation Partnership Project (3GPP) standardization organization introduces a downlink enhancement technology, i.e., the High Speed Downlink Packet Access (HSDPA) technology, under the version of Release 5.
The HSDPA technology introduces a new transmission channel, i.e., the High-Speed Downlink Shared Channel (HS-DSCH), to support enhanced access bearer services of interaction type, backstage type, and streaming media type. Meanwhile, in order to complete control, dispatching and feedback of corresponding HS-DSCH, the HSDPA technology introduces at the physical layer, a Shared Control Channel for HS-DSCH (HS-SCCH) and a High Speed Dedicated Physical Control Channel (HS-DPCCH) including uplink and downlink physical control channels, so as to directly and quickly complete the signaling interaction between User Equipment (UE) and a base station (Node B).
The HSDPA technology introduces a MAC-hs/ehs entity at the Media Access Control (MAC) of the UE and the Node B to complete related functions such as dispatching, feedback, and retransmission. With the performance of Fast Hybrid Automatic Repeat request (Fast Hybrid ARQ) and the direct control by the Node B, the retransmission speed is increased, and the data transmission delay is reduced.
However, under many occasions, for example, in the downtown area or the valley area, and when the UE moves at a high speed, the signal strength of the source cell fades fast; at the preparation stage of serving cell handover, especially when the radio link is reconfigured, the prior art repeats corresponding configurations of HSDPA parameters, and there is a long delay for transmitting the reconfiguration signaling and waiting for the corresponding response message, thus extra delay is brought for the serving cell handover; as a result, the handover message of the serving cell cannot be transmitted from the source cell to the UE, and the serving cell handover cannot be carried out, which causes a high drop call rate; in addition, as the time for HS-DSCH serving cell handover is too long, the service is suspended for a long time, which degrades the user's experience in real-time services such as Voice over Internet Protocol (VoIP) or Circuit Switched over High-Speed Packet Access (CS over HSPA).